Sequential read/write performances are becoming an important benchmark on disc drives used for audio and video applications. These performances are measured in terms of the rate of transfer between the host and drive in megabytes/second. In order to maximize the rate of transfer, the rotational latency of the drive needs to be minimized. After a read/write head has settled on a track and is adequately aligned with the track to read or write, there is an additional time, called latency, before the head actually begins to read or write data. Latency time is a time spent waiting for the disc to rotate such that the rotational sector that is to be read or written is aligned with the read/write head. Rotational latency is reduced by arranging the starting sector of the next head/track of the drive such that it is skewed. With a track skew adjusted to optimize read operation, the read/write head of the drive switches to the next head or seeks to the next track just in time to read the beginning of the next sequence of sectors on the new track. When not optimized, it is possible for the read/write head to miss the first sector of the next track and thus need to waste a disc revolution for the required sector to come round again to read. This caused the sequential read performance of the drive to fall. A similar problem occurs with write operations.
A method and apparatus are needed to improve the rate of transfer of data in disc drives and to reduce or eliminate latency in both sequential read and write operations of the disc drive.